Editorial

A sedentary lifestyle has been characterized as an independent risk factor for cardiovascular
disease [1]. Many studies have shown the inverse association between physical activity level and
the incidence of cardiovascular diseases [2-4]. Low aerobic fitness is a strong predictor for future
cardiovascular disease and all-cause mortality in both healthy and cardiovascular disease patients,
including those with hypertension [5-7]. Various mechanisms could be involved in the cardiovascular
protective effects of physical activity, including improvement in endothelial function, a decrease in
sympathetic neural activity and a reduction in arterial stiffness [8,9].
Hypertension is one of the most important risk factors for cardiovascular disease, and has
been ranked as the leading cause for death and disability worldwide: therefore, adequate control of
blood pressure is important for public health [10]. Lowering of blood pressure and prevention of
hypertension is in first instance preferable by lifestyle changes. These include weight loss, moderation
of alcohol intake, a diet with increased fresh fruit and vegetables, reduced saturated fat, reduced salt
intake, reduced stress, and, finally, increased physical activity [11,12]. With regard to the latter,
former guidelines predominantly recommended aerobic exercises such as walking, jogging, and
cycling for lowering blood pressure.
Even if drug therapy remains the mainstay of hypertension management, on the other hand
blood pressure control goes beyond adherence with drug therapy as there are other associated factors
[13], and achieving adequate blood pressure control with antihypertensive medication remains an
elusive goal for many patients anyway [14]. Furthermore, medical management of hypertension is
often complicated by concomitant comorbid conditions such as dyslipidaemia, hyperinsulinaemia,
glucose intolerance, reduced arterial compliance, sympathetic over-activity and obesity; for instance,
some antihypertensive agents adversely affect other cardiovascular risk factors, and adherence to
medication is often a problem. However, lifestyle changes improve multiple risk factors without
any side effects [15,16], and physical exercise has been demonstrated as a positive and effective
adjunct to other lifestyle measures in the prevention and management of hypertension [17]. As a
consequence, physical activity is recommended as prevention, treatment, and control of all stages
of hypertension [18-21], and therefore both the American Heart Association and the American
College of Sports Medicine have endorsed the inclusion of resistance training as an integral part
of an exercise program for promoting health and preventing cardiovascular disease [22,23], in
fact, continuous exercise training is the type of physical activity most frequently recommended to
hypertensive subjects [19], and in some patients regular aerobic exercise also reduces or eliminates
the need for antihypertensive medication [24].
In a previous systematic review with meta-analysis provided by Cornelissen et al. [25] the authors
reviewed the effect of resistance training on blood pressure and other cardiovascular risk factors in
adults, and the findings suggested that both moderate-intensity dynamic resistance training and lowintensity
isometric resistance training may cause a reduction in systolic and diastolic blood pressure;
furthermore, dynamic resistance training favorably affected some other cardiovascular risk factors
such as an increase in peak VO2 and a reduction in body fat and plasma triglycerides. The clinical
importance of these blood pressure reductions can be estimated from large, prospective intervention
studies investigating morbidity and mortality outcomes that suggest that small reductions in resting
systolic and diastolic blood pressure of 3 mmHg can reduce coronary heart disease risk by 5%, stroke by 8%, and all-cause mortality by 4% [26-28].
Moreover, given that the association between blood pressure
and cardiovascular risk has no lower threshold, reductions of this
magnitude in individuals with even optimal blood pressure at
baseline still seem to have clinical significance [11], and this strongly
underlines the potential of resistance training as adjuvant therapy for
the prevention and treatment of high blood pressure. In addition,
the positive effect of resistance training on other cardiovascular
risk factors suggest that a better physical fitness is associated with
a lower risk of all-cause mortality and cardiovascular events and is
independently associated with longevity [18,29]: aerobic exercise
not only reduces blood pressure, it also lowers levels of low-density
lipoprotein cholesterol, reduces insulin resistance and glucose
intolerance, and often is associated with reduced body weight [30].
Finally, it must be reminded that although genetic predisposition is
a risk factor for hypertension, studies have shown that behavioural
factors, such as sedentary lifestyle, overshadow genetic predisposition
as a cause of hypertension [31].
To prescribe resistance training as a potential tool in the
control of blood pressure, one should know how different training
characteristics influence the blood pressure response. Aerobic or
endurance exercises are dynamic physical exercises, involving large
muscle groups, which increase cardio-respiratory fitness and help
in weight control. They are those in which the exercising muscles
make use of oxygen. Aerobic exercises are effective in lowering blood
pressure or preventing hypertension [19]. These endurance activities,
such as walking, swimming, cycling and low-impact aerobics
(dancing or rope skipping), are the core of the exercise programme
for managing hypertension. The blood pressure responses to aerobic
exercises depend on the activities engaged in. Several studies have
shown that high-intensity aerobic interval training improves aerobic
fitness and reduces several cardiovascular risk factors more than
moderate intensity continuous training [32-36]. Although a large body
of evidences suggests that vigorous training compared to moderateand
low-intensity training elicits more cardiovascular benefits, also in
hypertensive patients [37,38], several meta-analyses indicate little or
no intensity-dependent effect of exercise training for the reduction of
the blood pressure [18,19,39]. In studies where low and high intensity
training programmes have been directly compared, the lower
intensity programmes were either more effective [40] or as effective
[41] as the higher intensity programmes, but more recent reviews
[28,42] reported no influence of exercise intensity on blood pressure
reduction following exercise treatment. Further, aerobic exercise
training of 60–85% of age-predicted (220-age in years) maximal
heart rate may be as, or more, effective as high-intensity exercise
in lowering BP in hypertensive patients [43]. As a consequence,
no specific guidelines delineate exercise intensity and frequency,
but a recent study performed by Molmen-Hansen et al. [44] study
indicates that the exercise-induced lowering effect of blood pressure
is intensity dependent: in addition, high-intensity aerobic interval
training was superior to moderate intensity continuous training in
terms of improved cardiac and endothelial function, aerobic capacity,
and heart rate recovery, and so aerobic interval training should be
viewed as an effective method to lower blood pressure and improve
other cardiovascular risk factors. Moreover, a growing body of
evidences suggests and our results also confirm the positive impact
of exercise training on both left and right ventricular systo-diastolic
function, in terms of subclinical improvement, in pharmacologically
treated hypertensive patients [9], and it must be reminded that given the poor blood pressure control in the general population and the
enormous prevalence of hypertension the possible means and process
of aerobic exercise complementing antihypertensive drug therapy in
order to achieve higher blood pressure control rates would place a
large number of people at decreased risk for cardiovascular morbidity
and mortality and so would have enormous implications and would
be of considerable and growing global public health importance.
In conclusion, there is an the ample evidence in the literature
that aerobic exercise lowers blood pressure in individuals with
hypertension. This is expected to encourage physicians to recommend
or refer people with hypertension, especially those who require more
than two antihypertensive drugs to achieve blood pressure control, for
aerobic exercise. Increased attention needs to be placed on strategies
to maintain or improve fitness, efforts to encourage physical activity
should urgently be intensified and supported, and sedentary lifestyle
should be viewed as one of several major modifiable risk factors in the
prevention and management of cardiovascular disease. Considering
the dearth of studies on the possible additive or complementary effect
of aerobic exercise on antihypertensive drug therapy in achieving
blood pressure control, more empirical studies are needed to make
an assertion about the role of aerobic exercise, in conjunction with
antihypertensive drug therapy, in achieving blood pressure control.